Types of MS

MS starts in 1 of 2 general ways: with individual relapses (attacks or exacerbations) or with gradual progression.

Relapsing remitting MS

More than 8 out of every 10 people with MS are diagnosed with the relapsing remitting type.

Someone with relapsing remitting MS will have episodes of new or worsening symptoms, known as relapses.

These typically worsen over a few days, last for days to weeks to months, then slowly improve over a similar time period.

Relapses often occur without warning, but are sometimes associated with a period of illness or stress.

The symptoms of a relapse may disappear altogether, with or without treatment, although some symptoms often persist, with repeated attacks happening over several years.

Periods between attacks are known as periods of remission. These can last for years at a time.

After many years (usually decades), many, but not all, people with relapsing remitting MS go on to develop secondary progressive MS.

In this type of MS, symptoms gradually worsen over time without obvious attacks. Some people continue to have infrequent relapses during this stage.

Around half of people with relapsing remitting MS will develop secondary progressive MS within 15 to 20 years, and the risk of this happening increases the longer you have the condition.

Primary progressive MS

Just over 1 in 10 people with the condition start their MS with a gradual worsening of symptoms.

In primary progressive MS, symptoms gradually worsen and accumulate over several years, and there are no periods of remission, though people often have periods where their condition appears to stabilise.

What causes MS?

MS is an autoimmune condition. This is when something goes wrong with the immune system and it mistakenly attacks a healthy part of the body – in this case, the brain or spinal cord of the nervous system.

In MS, the immune system attacks the layer that surrounds and protects the nerves called the myelin sheath.

This damages and scars the sheath, and potentially the underlying nerves, meaning that messages travelling along the nerves become slowed or disrupted.

Exactly what causes the immune system to act in this way is unclear, but most experts think a combination of genetic and environmental factors is involved.